Temperature reducing valve cascade control system and method based on improved internal model-active disturbance rejection controller

Abstract

The invention discloses a temperature reducing valve cascade control system and method based on an improved internal model-active disturbance rejection controller. The system comprises a first comparator, an internal model controller, the improved active disturbance rejection controller, a temperature reducing valve, a temperature sensor, a superheater, a temperature sensor and a fifth comparator which are sequentially arranged. According to the method, the main steam temperature control quality of transient working conditions such as peak regulation and frequency modulation of the thermal power generating unit can be remarkably improved; the improved ADRC is adopted in an inner ring of the cascade system to estimate and compensate disturbance in real time, and compared with PID control, the improved ADRC is more suitable for the complex multi-source characteristic of main steam temperature disturbance, and the anti-interference capability of the system can be improved; and internal model control is adopted in an outer ring of the cascade system, compared with PID control, the internal model control has a better control effect on the characteristics of large inertia and large delay of the main steam temperature, and the set value tracking performance of the system can be improved.

Description

Technical Field

[0001] The invention relates to the field of industrial automatic control, and in particular to a temperature reducing valve cascade control system and method based on an improved internal model-auto disturbance rejection controller. Background Art

[0002] The temperature reducing valve is an important part of the main steam temperature control system of thermal power units. It sprays the cooling water directly into the steam flow after atomization, and controls the cooling effect by changing the valve opening to control the amount of cooling water sprayed in. The control effect of the temperature reducing valve affects the regulation quality of the main steam temperature to a considerable extent. If the temperature reducing valve moves too quickly, the main steam temperature will fluctuate; if the temperature reducing valve moves too slowly, the main steam temperature will face the risk of overheating.

[0003] With the construction of new power systems, thermal power needs to frequently adjust the peak and frequency, and the main steam temperature will fluctuate significantly. The system has higher and higher requirements for the accuracy and speed of the temperature reduction valve position control. At present, most of the temperature reduction valve control systems in China still use the traditional PID cascade control algorithm. The PID control algorithm has the advantages of simple principle and easy implementation, wide application range and strong robustness. However, the main steam temperature system is a typical large time lag, multi-disturbance, nonlinear thermal system, superimposed with the nonlinearity and time-varying nature of the valve position control itself. Under the traditional cascade PID control strategy, steam temperature overheating often occurs, and it is difficult to obtain satisfactory control effects. Therefore, it is necessary to further study the control method based on advanced algorithms.

[0004] In addition, the current research and application of temperature reduction valve control systems at home and abroad are all under normal operating conditions of the unit, when the unit operating parameters are stable, nonlinearity and time lag are small, and disturbances are less. However, under deep peak-shaving and frequency-regulating conditions, the heat is unevenly distributed in time and space, the disturbances are more multi-source and complex, and the main steam temperature fluctuations are more severe. The existing temperature reduction valve control method based on advanced control algorithms is not specially designed for deep peak-shaving conditions. Sun Ming, Dong Ze, et al. proposed a temperature reduction valve control method based on cascade auto-disturbance rejection predictive control in the steam temperature system of secondary reheat units [J] (China Electric Power, 2018, 51(12): 118-123). The auto-disturbance rejection algorithm has excellent disturbance-overcoming ability and nonlinear adaptability to improve the control quality of the main steam temperature. However, the auto-disturbance rejection controller is not very adaptable to objects with large time lags and must rely on predictive control algorithms to compensate, making the system dependent on a more accurate model.

[0005] In summary, the current control system of the temperature reducing valve has the following technical problems: 1. Due to the large time lag, multiple disturbances and nonlinearity of the main steam temperature object and valve position control, under the traditional cascade PID control strategy, steam temperature over-temperature phenomenon often occurs, and it is difficult to obtain a satisfactory control effect; 2. Under deep peak load conditions, disturbances are more complex and multi-source, and time lags are greater. Various temperature reduction valve control algorithms based on advanced algorithms in existing research are not specially designed for this condition.

[0006] 3. The use of an auto-disturbance rejection controller to replace the PID controller makes it more capable of overcoming multi-source disturbances and nonlinearity of the controlled object. However, due to the auto-disturbance rejection controller's inadaptability to objects with large time lags, the auto-disturbance rejection controller has poor adaptability to the main steam temperature object. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a cascade control system and method of a temperature reducing valve based on an improved internal model-anti-disturbance control controller, which aims to solve the problems of poor effect of traditional cascade PID under large time lag, nonlinearity and multiple disturbances in main steam temperature control and how to improve advanced algorithms in a targeted manner under deep peak regulation conditions.

[0008] In order to achieve the above object, the present invention adopts the following technical solution: A temperature-reducing valve cascade control system based on an improved internal model-auto-disturbance rejection controller comprises a first comparator, an internal model controller, an improved auto-disturbance rejection controller, a temperature-reducing valve, a temperature sensor, a superheater, a temperature sensor and a fifth comparator which are arranged in sequence; The improved anti-disturbance controller includes a phase corrector, a tracking differentiator, a second comparator, a third comparator, a nonlinear controller, an expansion observer, a fourth comparator and a lag time reducer; the first comparator is unidirectionally connected to the internal model controller, the internal model controller is respectively connected to the phase corrector and the fifth comparator, the phase corrector is unidirectionally connected to the tracking differentiator, the tracking differentiator is respectively unidirectionally connected to the second comparator and the third comparator, the second comparator and the third comparator are unidirectionally connected to the nonlinear controller, the nonlinear controller is respectively unidirectionally connected to the temperature reduction valve and the expansion observer, the temperature reduction valve is respectively unidirectionally connected to the lag time reducer and the superheater, the lag time reducer is respectively unidirectionally connected to the expansion observer and the superheater, the expansion observer is respectively unidirectionally connected to the second comparator and the third comparator, the superheater is unidirectionally connected to the temperature sensor, the temperature sensor is unidirectionally connected to the fourth comparator, and the fourth comparator is unidirectionally connected to the first comparator.

[0009] A further improvement of the present invention is that an internal model controller is used to replace the PID controller as the main loop controller of the cascade control system.

[0010] A further improvement of the present invention is that the internal model controller receives the steam temperature deviation ∆ After the signal is received, the outlet temperature setting value of the temperature reducing valve is obtained through calculation. And main steam temperature without time lag estimated temperature , and are sent to the improved active disturbance rejection controller and the fourth comparator respectively.

[0011] A further improvement of the present invention is that an improved active disturbance rejection controller is used to replace the PID controller as the secondary loop controller of the cascade control system.

[0012] A further improvement of the present invention is that the improved self-disturbance rejection controller receives the current temperature setting value of the temperature reduction valve outlet sent by the internal model controller. , after calculation, the control amount of the temperature reduction valve is obtained , and sent to the modified desuperheating valve to adjust the opening to adjust the main steam temperature.

[0013] A further improvement of the present invention is that in the improved anti-disturbance control device, the phase corrector receives the temperature setting value of the outlet temperature of the temperature reducing valve. , perform phase advance correction, and calculate the temperature setting value of the cooling valve outlet after phase correction , transmitted to the tracking differentiator; the tracking differentiator receives the temperature setting value of the cooling valve outlet after phase correction , calculated Tracking value of and differential value , transmitted to the tracking second comparator and the third comparator; the second comparator and the third comparator receive the tracking value output by the tracking differentiator respectively and differential value And the expansion observer outputs the observed value of the temperature reduction valve outlet temperature and differential value , calculate the deviation ,deviation ,deviation The nonlinear controller receives the deviation of the output of the second comparator and the third comparator. ,deviation ,deviation , after the nonlinear function is activated, the output control quantity , transmitted to the cooling valve and the lag time reducer; the lag time reducer receives the actual value of the cooling valve outlet temperature measured by the temperature sensor after the cooling valve , calculate the small hysteresis prediction value of the outlet temperature of the cooling valve ; The extended observer receives the output control quantity from the nonlinear observer The predicted value of the outlet temperature of the desuperheater valve output by the delay time reducer , calculate the observed value of the outlet temperature of the cooling valve and differential value .

[0014] A further improvement of the present invention is that an improved phase corrector of the self-disturbance rejection controller is used to make an advance estimate of the main steam temperature and improve the nonlinear characteristics of the main steam temperature.

[0015] A further improvement of the present invention is that an improved delay time reducer of the auto-disturbance rejection controller is used to reduce the time lag characteristic of the valve action.

[0016] A cascade control method for a temperature reducing valve based on an improved internal model-auto disturbance rejection controller includes: Step 1: Assume the current time is n, and set the main steam temperature setting value , transmitted to the first comparator, the temperature sensor measures the actual temperature of the main steam temperature , the fourth comparator outputs the actual temperature of the main steam temperature The estimated temperature without time lag with the output of the internal model controller Deviation , transmitted to the first comparator; Fourth comparator output deviation The calculation formula is as follows:

[0017] Step 2: The first comparator outputs the fourth comparator Main steam temperature set value at the time , compare and calculate to get the current steam temperature deviation ; Current steam temperature deviation ∆ The calculation formula is as follows:

[0018] Step 3: The internal model controller receives the current steam temperature deviation ∆ After the signal is calculated, the following two outputs are obtained: the set value of the outlet temperature of the temperature reducing valve at time n And main steam temperature without time lag estimated temperature ; Step 4: Improve the ADRC to receive the temperature setting value of the desuperheating valve outlet temperature sent by the internal model controller After the phase corrector, tracking differentiator, second comparator and third comparator, nonlinear controller, expansion observer and lag time reducer, the temperature reduction valve position control quantity is obtained. ; Step 5: The temperature reduction valve receives the valve position control quantity sent by the improved anti-disturbance control controller , by changing the valve position and the amount of water sprayed, the main steam temperature is adjusted, and the actual value of the temperature at the outlet of the temperature reducing valve is obtained from the temperature sensor ; After passing through the superheater, the main steam temperature at time n+1 is measured by the temperature sensor. ; Step 6: The fourth comparator receives the main steam temperature at time n+1 measured by the temperature sensor The internal model controller calculates the time-delay-free estimate of the superheater outlet temperature at time n+1 , compare and calculate, and get the output deviation at the previous moment , and is sent back to the first comparator for calculation.

[0019] A further improvement of the present invention is that the specific implementation method of step 4 includes: First, the phase corrector receives the temperature setting value of the desuperheating valve outlet , perform phase advance correction on it, and obtain the temperature setting value of the cooling valve outlet after phase correction ; Temperature setting value of the temperature reducing valve outlet after phase correction The calculation formula is as follows:

[0020] in, is the system lead time, is the lag time, ; Secondly, the tracking differentiator receives the temperature setting value of the cooling valve outlet after phase correction , calculated Tracking value of and differential value ; Tracking value of and differential value The calculation formula is as follows:

[0021]

[0022] Where h is the sampling time, fhan is the fastest comprehensive function; Secondly, the second and third comparators receive the tracking value output by the tracking differentiator respectively and differential value And the expansion observer outputs the observed value of the temperature reduction valve outlet temperature and differential value , calculate the deviation ,deviation ,deviation ; deviation ,deviation ,deviation The calculation formula is as follows:

[0023]

[0024]

[0025] Secondly, the nonlinear controller receives the deviation of the outputs of the second comparator and the third comparator ,deviation ,deviation , after the nonlinear function is activated, the output control quantity ; Control volume The calculation formula is as follows:

[0026] In the formula, is an adjustable parameter, f is a nonlinear activation function, , ; The calculation formula of f is as follows:

[0027] The extended observer receives the output control quantity from the nonlinear observer The predicted value of the outlet temperature of the desuperheater valve output by the delay time reducer , calculate the observed value of the outlet temperature of the cooling valve and differential value ; and The calculation formula is as follows:

[0028] In the formula, is the dilated observable of the disturbance, is an adjustable parameter, It is the actual value of the outlet temperature of the cooling valve measured by the temperature sensor behind the cooling valve; Secondly, the delay time reducer receives the actual value of the outlet temperature of the cooling valve measured by the temperature sensor after the cooling valve. , calculate the small hysteresis prediction value of the outlet temperature of the cooling valve ; The calculation formula is as follows:

[0029] In the formula, To estimate the lag time, it is obtained through valve performance testing.

[0030] Compared with the prior art, the present invention has at least the following beneficial technical effects: The present invention provides a desuperheating valve cascade control system and method based on an improved internal model-auto-disturbance rejection controller. The present invention can significantly improve the main steam temperature control quality of transient working conditions such as peak-shaving and frequency modulation of thermal power units; the improved ADRC is used in the inner loop of the cascade system to estimate and compensate for disturbances in real time, which is more suitable for the complex and multi-source characteristics of the main steam temperature disturbance than PID control, and can improve the system's anti-disturbance ability; the internal model control is used in the outer loop of the cascade system, which has a better control effect on the large inertia and large delay characteristics of the main steam temperature than PID control, and can improve the system's set value tracking performance; in the improved ADRC controller, the designed lag time reducer can reduce the lag of steam-water mixing desuperheating, and convert the main steam temperature object from a large time-delay object to a small time-delay object, so that the nonlinear characteristics of the system are reduced, effectively compensating for the problem that the auto-disturbance rejection controller is not adaptable to large time-delay objects. In the improved auto-disturbance rejection controller, the designed phase corrector can increase the phase margin and amplitude margin of the system, improve the stability of the main steam temperature system, and improve the rapidity of the system response. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 Schematic diagram of the temperature reduction valve cascade control system based on the improved internal model-auto-disturbance rejection controller.

[0033] Figure 2 Schematic diagram of the improved ADRC controller.

[0034] Figure 3 This is the control flow chart of the temperature reduction valve cascade control system.

[0035] Figure 4 Comparison chart of the effect of improving the active disturbance rejection controller. DETAILED DESCRIPTION

[0036] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0037] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0038] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0039] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0040] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0041] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0042] Example 1 The desuperheating valve cascade control system based on the improved internal model-auto-disturbance rejection controller provided by the present invention comprises a first comparator, an internal model controller, an improved auto-disturbance rejection controller, a desuperheating valve, a temperature sensor, a superheater, a temperature sensor and a fifth comparator which are arranged in sequence; the improved auto-disturbance rejection controller comprises a phase corrector, a tracking differentiator, a second comparator, a third comparator, a nonlinear controller, an expansion observer, a fourth comparator and a lag time reducer; the first comparator is unidirectionally connected to the internal model controller, the internal model controller is respectively connected to the phase corrector and the fifth comparator, the phase corrector and the tracking differentiator are connected to the phase corrector and the fifth comparator, and the phase corrector and the tracking differentiator are connected to the phase corrector and the fifth comparator. The differential is unidirectionally connected to the second comparator and the third comparator respectively, the second comparator and the third comparator are unidirectionally connected to the nonlinear controller, the nonlinear controller is unidirectionally connected to the temperature reducing valve and the expansion observer respectively, the temperature reducing valve is unidirectionally connected to the lag time attenuator and the superheater respectively, the lag time attenuator is unidirectionally connected to the expansion observer and the superheater respectively, the expansion observer is unidirectionally connected to the second comparator and the third comparator respectively, the superheater is unidirectionally connected to the temperature sensor, the temperature sensor is unidirectionally connected to the fourth comparator, and the fourth comparator is unidirectionally connected to the first comparator.

[0043] In this embodiment, an internal model controller is used to replace the PID controller as the main loop controller of the cascade control system; the internal model controller receives the steam temperature deviation ∆ After the signal is received, the outlet temperature setting value of the temperature reducing valve is obtained through calculation. And main steam temperature without time lag estimated temperature , and are sent to the improved anti-disturbance controller and the fourth comparator respectively; the internal model controller, as the main controller of the cascade control system, can improve the system's ability to track the set value.

[0044] In this embodiment, an improved anti-disturbance control controller is used to replace the PID controller as the secondary loop controller of the cascade control system; the improved anti-disturbance control controller receives the current temperature setting value of the temperature reduction valve outlet sent by the internal model controller. , after calculation, the control amount of the temperature reduction valve is obtained , and sent to the modified desuperheating valve to adjust the opening to adjust the main steam temperature; the improved anti-disturbance controller as the sub-controller of the cascade control system can improve the system's ability to overcome disturbances.

[0045] In this embodiment, the improved anti-disturbance controller includes a phase corrector, a tracking differentiator, a second comparator, a third comparator, a nonlinear controller, an extended observer, a fourth comparator and a lag time reducer; the phase corrector receives the temperature setting value of the temperature reduction valve outlet. , perform phase advance correction, and calculate the temperature setting value of the cooling valve outlet after phase correction , transmitted to the tracking differentiator; the tracking differentiator receives the temperature setting value of the cooling valve outlet after phase correction , calculated Tracking value of and differential value , transmitted to the tracking second comparator and the third comparator; the second and third comparators receive the tracking value output by the tracking differentiator respectively and differential value And the expansion observer outputs the observed value of the temperature reduction valve outlet temperature and differential value , calculate the deviation ,deviation ,deviation The nonlinear controller receives the deviation of the output of the second comparator and the third comparator. ,deviation ,deviation , after the nonlinear function is activated, the output control quantity , transmitted to the cooling valve and the lag time reducer; the lag time reducer receives the actual value of the cooling valve outlet temperature measured by the temperature sensor after the cooling valve , calculate the small hysteresis prediction value of the outlet temperature of the cooling valve ; The extended observer receives the output control quantity from the nonlinear observer The predicted value of the outlet temperature of the desuperheater valve output by the delay time reducer , calculate the observed value of the outlet temperature of the cooling valve and differential value .

[0046] In this embodiment, the improved phase corrector of the active disturbance rejection controller can make an advance prediction of the main steam temperature and improve the nonlinear characteristics of the main steam temperature.

[0047] In this embodiment, the improved delay time reducer of the anti-disturbance controller can reduce the time lag characteristics of the valve action and improve the rapidity and accuracy of the valve response.

[0048] In this embodiment, the improved ADRC with integrated phase compensator and lag time reducer eliminates the oscillation problem of the ADRC controller caused by the hysteresis link while retaining the ADRC's ability to reduce overshoot, adjust time and improve dynamic performance.

[0049] In this embodiment, the temperature reduction valve cascade control system based on the improved internal model-anti-disturbance rejection controller has better set point tracking capability, robustness and anti-disturbance capability than the traditional PID cascade control system.

[0050] Example 2 The present invention provides a method for controlling a temperature-reducing valve cascade based on an improved internal model-auto disturbance rejection controller, and the specific steps are as follows: Step 1: Assume the current time is n, and set the main steam temperature setting value , transmitted to the first comparator, the temperature sensor measures the actual temperature of the main steam temperature , the fourth comparator outputs the actual temperature of the main steam temperature The estimated temperature without time lag with the output of the internal model controller Deviation , transmitted to the first comparator.

[0051] Fourth comparator output deviation The calculation formula is as follows:

[0052] Step 2: The first comparator outputs the fourth comparator Main steam temperature set value at the time , compare and calculate to get the current steam temperature deviation ; Current steam temperature deviation ∆ The calculation formula is as follows:

[0053] Step 3: The internal model controller receives the current steam temperature deviation ∆ After the signal is calculated, the following two outputs are obtained: the set value of the outlet temperature of the temperature reducing valve at time n And main steam temperature without time lag estimated temperature .

[0054] Step 4: Improve the ADRC to receive the temperature setting value of the desuperheating valve outlet temperature sent by the internal model controller After the phase corrector, tracking differentiator, second comparator and third comparator, nonlinear controller, expansion observer and lag time reducer, the temperature reduction valve position control quantity is obtained. .

[0055] First, the phase corrector receives the temperature setting value of the desuperheating valve outlet , perform phase advance correction on it, and obtain the temperature setting value of the cooling valve outlet after phase correction .

[0056] Temperature setting value of the temperature reducing valve outlet after phase correction The calculation formula is as follows:

[0057] in, is the system lead time, is the lag time, .

[0058] Secondly, the tracking differentiator receives the temperature setting value of the cooling valve outlet after phase correction , calculated Tracking value of and differential value .

[0059] Tracking value of and differential value The calculation formula is as follows:

[0060]

[0061] Where h is the sampling time and fhan is the fastest integrated function.

[0062] Secondly, the second and third comparators receive the tracking value output by the tracking differentiator respectively and differential value And the expansion observer outputs the observed value of the temperature reduction valve outlet temperature and differential value , calculate the deviation ,deviation ,deviation .

[0063] deviation ,deviation ,deviation The calculation formula is as follows:

[0064]

[0065]

[0066] Secondly, the nonlinear controller receives the deviation of the outputs of the second comparator and the third comparator ,deviation ,deviation , after the nonlinear function is activated, the output control quantity .

[0067] Control volume The calculation formula is as follows:

[0068] In the formula, is an adjustable parameter, f is a nonlinear activation function, , .

[0069] The calculation formula of f is as follows:

[0070] The extended observer receives the output control quantity from the nonlinear observer The predicted value of the outlet temperature of the desuperheater valve output by the delay time reducer , calculate the observed value of the outlet temperature of the cooling valve and differential value .

[0071] and The calculation formula is as follows:

[0072] In the formula, is the dilated observable of the disturbance, is an adjustable parameter, It is the actual value of the outlet temperature of the cooling valve measured by the temperature sensor behind the cooling valve.

[0073] Secondly, the delay time reducer receives the actual value of the outlet temperature of the cooling valve measured by the temperature sensor after the cooling valve. , calculate the small hysteresis prediction value of the outlet temperature of the cooling valve The calculation formula is as follows:

[0074] In the formula, To estimate the lag time, valve performance testing can be performed.

[0075] Step 5: The temperature reduction valve receives the valve position control quantity sent by the improved anti-disturbance control controller , by changing the valve position and the amount of water sprayed, the main steam temperature is adjusted, and the actual value of the temperature at the outlet of the temperature reducing valve is obtained from the temperature sensor . After passing through the superheater, the main steam temperature at time n+1 is measured by the temperature sensor. .

[0076] Step 6: The fourth comparator receives the main steam temperature at time n+1 measured by the temperature sensor The internal model controller calculates the time-delay-free estimate of the superheater outlet temperature at time n+1 , compare and calculate, and get the output deviation at the previous moment . It is sent back to the first comparator for calculation.

[0077] In summary, the valve position cascade control method of the present invention adopts a cascade control strategy, and the control effect is shown in Figure 4. First, after the secondary loop adopts ADRC and GADRC, it changes from underdamping to overdamping compared with PID control, the overshoot of the response curve disappears, and the adjustment time is significantly shortened, which proves that ADRC and GADRC can effectively improve the control effect of the secondary loop. Compared with ADRC and GADRC, the adjustment time of ADRC is shorter, and it can be seen from the small figure captured in the box that GADRC can effectively eliminate the oscillation problem of the ADRC controller caused by the hysteresis link. That is, the GADRC controller with integrated phase compensator and lag time reducer eliminates the oscillation problem of the ADRC controller caused by the hysteresis link while retaining the ADRC controller to reduce overshoot, adjust time and improve dynamic performance.

[0078] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0079] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A cascade control system of a temperature reducing valve based on an improved internal model-auto disturbance rejection controller, characterized in that: It includes a first comparator, an internal model controller, an improved anti-disturbance controller, a temperature reduction valve, a temperature sensor, a superheater, a temperature sensor and a fifth comparator which are arranged in sequence; The improved anti-disturbance controller includes a phase corrector, a tracking differentiator, a second comparator, a third comparator, a nonlinear controller, an expansion observer, a fourth comparator and a lag time reducer; the first comparator is unidirectionally connected to the internal model controller, the internal model controller is respectively connected to the phase corrector and the fifth comparator, the phase corrector is unidirectionally connected to the tracking differentiator, the tracking differentiator is respectively unidirectionally connected to the second comparator and the third comparator, the second comparator and the third comparator are unidirectionally connected to the nonlinear controller, the nonlinear controller is respectively unidirectionally connected to the temperature reduction valve and the expansion observer, the temperature reduction valve is respectively unidirectionally connected to the lag time reducer and the superheater, the lag time reducer is respectively unidirectionally connected to the expansion observer and the superheater, the expansion observer is respectively unidirectionally connected to the second comparator and the third comparator, the superheater is unidirectionally connected to the temperature sensor, the temperature sensor is unidirectionally connected to the fourth comparator, and the fourth comparator is unidirectionally connected to the first comparator.

2. The desuperheating valve cascade control system based on improved internal model-auto disturbance rejection controller according to claim 1 is characterized in that: The internal model controller is used to replace the PID controller as the main loop controller of the cascade control system.

3. The desuperheating valve cascade control system based on improved internal model-auto disturbance rejection controller according to claim 2 is characterized in that: The internal model controller receives the current steam temperature deviation ∆ After the signal is received, the outlet temperature setting value of the temperature reducing valve is obtained through calculation. And main steam temperature without time lag estimated temperature , and are sent to the improved active disturbance rejection controller and the fourth comparator respectively.

4. The desuperheating valve cascade control system based on improved internal model-auto disturbance rejection controller according to claim 1 is characterized in that: An improved active disturbance rejection controller is used to replace the PID controller as the sub-loop controller of the cascade control system.

5. The temperature reducing valve cascade control system based on improved internal model-auto disturbance rejection controller according to claim 4 is characterized in that: The improved ADRC receives the current temperature setting value of the desuperheating valve outlet sent by the internal model controller. , after calculation, the control amount of the temperature reduction valve is obtained , and sent to the modified desuperheating valve to adjust the opening to adjust the main steam temperature.

6. The desuperheating valve cascade control system based on improved internal model-auto disturbance rejection controller according to claim 4 is characterized in that: In the improved ADRC, the phase corrector receives the set value of the outlet temperature of the temperature reducing valve. , perform phase advance correction, and calculate the temperature setting value of the cooling valve outlet after phase correction , transmitted to the tracking differentiator; the tracking differentiator receives the temperature setting value of the cooling valve outlet after phase correction , calculated Tracking value of and differential value , transmitted to the tracking second comparator and the third comparator; the second comparator and the third comparator receive the tracking value output by the tracking differentiator respectively and differential value And the expansion observer outputs the observed value of the temperature reduction valve outlet temperature and differential value , calculate the deviation ,deviation ,deviation ; The nonlinear controller receives the deviation of the outputs of the second comparator and the third comparator. ,deviation ,deviation , after the nonlinear function is activated, the output control quantity , transmitted to the cooling valve and the lag time reducer; the lag time reducer receives the actual value of the cooling valve outlet temperature measured by the temperature sensor after the cooling valve , calculate the small hysteresis prediction value of the outlet temperature of the cooling valve ; The extended observer receives the output control quantity from the nonlinear observer The predicted value of the outlet temperature of the desuperheater valve output by the delay time reducer , calculate the observed value of the outlet temperature of the cooling valve and differential value .

7. The desuperheating valve cascade control system based on improved internal model-auto disturbance rejection controller according to claim 1 is characterized in that: The improved phase corrector of the active disturbance rejection controller is used to make advance prediction of the main steam temperature and improve the nonlinear characteristics of the main steam temperature.

8. The temperature reducing valve cascade control system based on improved internal model-auto disturbance rejection controller according to claim 1 is characterized in that: The improved auto-disturbance rejection controller lag time reducer is used to reduce the time lag characteristics of valve action.

9. A cascade control method for a temperature reducing valve based on an improved internal model-auto disturbance rejection controller is characterized in that: include: Step 1: Assume the current time is n, and set the main steam temperature setting value , transmitted to the first comparator, the temperature sensor measures the actual temperature of the main steam temperature , the fourth comparator outputs the actual temperature of the main steam temperature The estimated temperature without time lag with the output of the internal model controller Deviation , transmitted to the first comparator; Fourth comparator output deviation The calculation formula is as follows: Step 2: The first comparator outputs the fourth comparator Main steam temperature set value at the time , compare and calculate to get the current steam temperature deviation ; Current steam temperature deviation ∆ The calculation formula is as follows: Step 3: The internal model controller receives the current steam temperature deviation ∆ After the signal is calculated, the following two outputs are obtained: the outlet temperature setting value of the temperature reduction valve at time n And main steam temperature without time lag estimated temperature ; Step 4: Improve the ADRC to receive the temperature setting value of the desuperheating valve outlet sent by the internal model controller After the phase corrector, tracking differentiator, second comparator and third comparator, nonlinear controller, expansion observer and lag time reducer, the temperature reduction valve position control quantity is obtained. ; Step 5: The temperature reduction valve receives the valve position control quantity sent by the improved anti-disturbance control controller , by changing the valve position and the amount of water sprayed, the main steam temperature is adjusted, and the actual value of the temperature at the outlet of the temperature reducing valve is obtained from the temperature sensor ; After passing through the superheater, the main steam temperature at time n+1 is measured by the temperature sensor. ; Step 6: The fourth comparator receives the main steam temperature at time n+1 measured by the temperature sensor The internal model controller calculates the time-delay-free estimate of the superheater outlet temperature at time n+1 , compare and calculate, and get the output deviation at the previous moment , and is sent back to the first comparator for calculation.

10. The method for controlling a temperature-reducing valve cascade based on an improved internal model-auto disturbance rejection controller according to claim 9, characterized in that: The specific implementation method of step 4 includes: First, the phase corrector receives the temperature setting value of the desuperheating valve outlet , perform phase advance correction on it, and obtain the temperature setting value of the cooling valve outlet after phase correction ; Temperature setting value of the temperature reducing valve outlet after phase correction The calculation formula is as follows: in, is the system lead time, is the lag time, ; Secondly, the tracking differentiator receives the temperature setting value of the cooling valve outlet after phase correction , calculated Tracking value of and differential value ; Tracking value of and differential value The calculation formula is as follows: In the formula, h is the sampling time, fhan is the fastest comprehensive function; Secondly, the second and third comparators receive the tracking value output by the tracking differentiator respectively and differential value And the expansion observer outputs the observed value of the temperature reduction valve outlet temperature and differential value , calculate the deviation ,deviation ,deviation ; deviation ,deviation ,deviation The calculation formula is as follows: Secondly, the nonlinear controller receives the deviation of the outputs of the second comparator and the third comparator ,deviation ,deviation , after the nonlinear function is activated, the output control quantity ; Control volume The calculation formula is as follows: In the formula, is an adjustable parameter, f is a nonlinear activation function, , ; The calculation formula of f is as follows: The extended observer receives the output control quantity from the nonlinear observer The predicted value of the outlet temperature of the desuperheater valve output by the delay time reducer , calculate the observed value of the outlet temperature of the cooling valve and differential value ; and The calculation formula is as follows: In the formula, is the dilated observable of the disturbance, is an adjustable parameter, It is the actual value of the outlet temperature of the cooling valve measured by the temperature sensor behind the cooling valve; Secondly, the delay time reducer receives the actual value of the outlet temperature of the cooling valve measured by the temperature sensor after the cooling valve. , calculate the small hysteresis prediction value of the outlet temperature of the cooling valve ; The calculation formula is as follows: In the formula, To estimate the lag time, it is obtained through valve performance testing.

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